Active feedback silicon failure analysis die temperature control system

Abstract

Fault analysis of high power integrated circuits face thermal management challenges. This invention employs thermal diodes incorporated in the device undergoing fault analysis, and a closed loop microprocessor controlled feedback system for thermal control during test and fault analysis.

What is claimed is: 
     
         1 . An integrated circuit test handler for a device undergoing failure analysis having at least one thermal diode comprising:
 a device under test board adapted to receive a integrated circuit for test;   an electrical connector for coupling to said at least one thermal diode on the integrated circuit;   a microcontroller connected to said electrical connector programmed to
 compare a temperature corresponding to signals from the at least one thermal diode on the integrated circuit to a temperature set point thereby generating an error signal, and 
 compute a solenoid drive signal from said error signal; 
   a source of cooling fluid;   a valve coupled to the source of cooling fluid, said valve having an open state supplying cooling fluid to bathe the integrated circuit and a closed state excluding cooling fluid from the integrated circuit; and   a solenoid receiving said solenoid drive signal and controlling the open/closed state of said valve.   
     
     
         2 . The integrated circuit test handler of  claim 1 , wherein:
 said cooling fluid is boiled liquid nitrogen.   
     
     
         3 . The integrated circuit test handler of  claim 1 , wherein:
 said cooling fluid is compressed air.   
     
     
         4 . The integrated circuit test handler of  claim 1 , further comprising:
 an I 2 C interface connected by said electrical connector to said at least one thermal diode generating a signal suitable for reading by said microcontroller.   
     
     
         5 . The integrated circuit test handler of  claim 4 , further comprising:
 said I 2 C interface is mounted on said device under test board.   
     
     
         6 . The integrated circuit test handler of  claim 5 , further comprising:
 said microcontroller is mounted on a circuit board separate from said device under test board.   
     
     
         7 . The integrated circuit test handler of  claim 1 , wherein:
 said microcontroller is programmed to compute a solenoid drive signal by
 forming a Proportional-Integral-Derivative function of said error signal, and 
 converting said Proportional-Integral-Derivative function into a pulse width modulated drive function for said solenoid. 
   
     
     
         8 . The integrated circuit test handler of  claim 1 , further comprising:
 a solenoid drive circuit connected to said microcontroller receiving said pulse width modulated drive function and generating an amplified solenoid drive function suitable for controlling said solenoid.   
     
     
         9 . The integrated circuit test handler of  claim 8 , wherein:
 said solenoid drive circuit includes an operational amplifier.   
     
     
         10 . The integrated circuit test handler of  claim 1 , further comprising:
 a lid with a central opening covering said integrated circuit and exposing the surface of said integrated circuit;   an inlet port on said lid operable to receive said cooling fluid;   a plurality of gas channels operable to evenly distribute said cooling fluid around the circumference of said lid;   a plurality of gas injection ports connected to said gas channels operable to distribute the cooling fluid to the surface of said integrated circuit.